I have heard quite a bit over the last few years that many folks use the LR primers in magnum chamberings. That being said,...how many of you have done this and what if any differences have you seen in the loads with respect to velocity, groups, and or extreme spread?

Thanks.

P.S. anyone use them in a RUM?

JustC, after I get a load shooting well w/ one make of primer, I'll often try diff. primer brands & mags vs std. It varies w/ each cart./rifle combo. Sometimes switching to a mag primer will tighten groups, sometimes open them up. Same thing w/ match vs. std. You'll just have to experiment.

JustC, are you talking about magnum pistol cartridges? The only one I've seen that recommended for is the .454 Casull, because of its rifle-level pressures that are too much for large pistol primers.

Slow burning ball powder works better with mag primers. Stick powders usually work ok with LR primers. Just try them and see what happens (safely).

muck

Primers can play a big part in the way a load preforms. The cartridge, powder, and bullet wt. combination will all respond differently to the primer change.
I would not consider using anything but large rifle mag. primers in my .375 H&H Mag. in fact I prefer Fed.#215s as they are hotter. This is a case of a large quantity of powder that needs positive ignition. My .222 Rem. and 22/250 Rem. both respond to mag. primers. The .222 is loaded with H335 and the 22/250 is loaded with Win.760. Both powders being ball type and are a little more difficult to ignite.
Extreme spreads in velocity with regard to the .222 and the 22/250 are cut from approx. 85-95 fps to 15-18 fps. the loads I have checked in my .308 Win. and .30-06 Sprg. are also notable, but not always in favor of the mag primer. The .308 does not like them at all. As with the .375 H&H, I would not use anything but mag. primers in my .257 Wby. Mag.(again large amount of powder).
The only way to know what the primer is doing your load is by shooting it over a cronagraph and on paper off a good bench. Be sure to check them out to at lest 200yds. Keep in mind that different brands also present a variable.
Watch your pressures, and good loading.

Yes,..I meant rifle calibers. Thanks so far for the responses.

I may just try a mag primer with my ball powders and see if that is an improvement.

anyone else???

I don't suppose you are interested in black powder loading, but over the last 5 yrs or so, there has been a strong shift away from magnums to regular rifle primers or even large pistol primers. There are some caveats with the pistol primers so I don't recommend them for your purposes.

The prevailing theory is that a heavy primer launches the bullet into the rifling prior to the detonation/ignition of the main powder charge. The result is inaccuracy for reasons that are not especially clear, at least to me. In any event, after quite a bit of extensive testing by numerous and accomplished shooters, the mildest primer possible is generally best.

So, the extent to which this might matter to your loads I can only guess, but firing a few primer-only cartridges might tell you a bit about the potential for this - might also result in a stuck bullet in your bore, so take that suggestion with a huge open-pit mine of salt.

Check out this webpage for some interesting primer tests as well. http://www.castingstuff.com/primer_tester.htm

Brent

Thanks Brent.

It seems a bit paradoxical that we use hotter primers to reduce muzzle velocity variation, yet the 6mm PPC was designed with a smaller than normal flash hole because Dr. Palmisano felt that the LEAST primer flame that would reliably ignite the powder gave the best accuracy. Many still believe that the extraordinary accuracy of the 6mm PPC is largely attributable to this. And in the old days before inline muzzleloaders and such came along, some insisted that flintlocks had better accuracy potential off a rest than percussion guns, because of the milder ignition that was more consistent. I don't know what this all means, just passing along some interesting stuff I've read.

That's interesting. Better flame penetration of the powder charge, perhaps?

The www.castingstuff.com primer test page was just updated with the new Russian primers.